Study On Catalytic Polyolefins Catalyzed By Asymmetric Diimine Nickel And Cationic Phosphonium Phosphate Phosphateng

In the past 50 years,research on olefin polymerization has achieved great success in both academia and industry.Polyolefins have a large annual output and are widely used,but they have non-polar characteristics,which greatly limits their use.By introducing a polar functional group into the polyolefin,its properties can be greatly improved,its use can be broadened,and its commercial value can be improved.The use of transition metal catalysts to achieve copolymerization of olefins with polar monomers is the most straightforward way to prepare functionalized polyolefin materials,and is also very challenging.This thesis mainly focuses on the improvement of existing catalyst systems,the design and preparation of new catalyst systems,the design of new polymerization control methods,the preparation and properties of special polyolefins and functionalized polyolefin materials.1.In this paper,a series of asymmetric α-diimine nickel complexes were prepared and characterized.The prepared nickel complex exhibits excellent properties in ethylene polymerization,including high activity,high thermal stability,and ability to produce high molecular weight polyethylene.At the same time,these nickel complexes are also active in the polymerization of α-olefins such as propylene,1-hexene,1-octene and1-decene.The chain walking characteristics of this catalyst lead to chain straightening in these polymerizations,which is very rare as a nickel catalyzed reaction,which has been shown to have propylene with polar monomers such as 10-undecenoic acid.The ability of a methyl ester to copolymerize with 10-undecen-1-ol.The paper also studied in detail the mechanical properties of polyethylene products,catalyst structure and polymerization conditions can significantly affect the tensile properties and elastic properties of polyethylene samples.These results are of great reference value for the future design of ligands,improvement of catalysts and the application of such catalysts to catalyze high-performance polymer materials.2.In this paper,palladium and nickel catalysts were constructed on the PNPO ligand platform,both of which can effectively mediate ethylene polymerization and copolymerization with basic polar monomers.The unique properties of this system stem from the short bite ligand platform,which can increase ligand rigidity.Furthermore,it has been found that the electronic asymmetric characteristics of ligands resulting from the combination of a strong σ-administered phosphine moiety and a weakσ-administered phosphine oxide moiety contribute to their unique properties.The groupis currently exploring other short-bore ligands with electronic asymmetry in order to find higher performance catalysts and general ligand design principles.